Some of the comments in the oildrum.com are really top quality information, but they vanish into the ethersphere far too quickly as the next day’s enormous comment thread commences.

Today shelburn did a great job explaining how to understand/interpret ROV video footage.

shelburn on May 24, 2010 – 11:20am Permalink | Subthread | Parent | [Parent subthread ] Comments top

VIEWING ROV VIDEO

Apologies to those who already read this on a previous thread.

There should be a short course in viewing ROV videos to go along with this live streaming. There is always a learning curve when a new oil company man comes onboard until he understands the peculiarities of ROV video. A lot of this is not intuitive and no one should feel stupid because things in the pictures confuse them. I’ll try to hit just a few of the highlights.

Debris in the picture – This area of the Gulf of Mexico is covered with incredibly fine soft mud. If an ROV is working near the bottom and he has to move upwards his thruster wash will hit the bottom and stir up this mud and any other light debris (hydrates, tar balls, strings of heavier petroleum products, etc). The currents at this depth are usually slow and it can take a long time, as much as 15 minutes or more, before the visibility clears. And if the ROV is working anywhere near the bottom it is very difficult not to occasionally kick up some mud.

There are a number of other ROVs working in the area (any light you might see is another ROV vehicle or cage). So if any ROV upcurrent from the one feeding the live video stream kicks up some mud and debris that will drift over the area and cloud or obscure the picture.
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Took a while before we saw some decent attempts at journalism being done, here’s a new article from the Orlando Sentinel. Make sure to read ROCKMAN’s response at the end of this posting.

By Kevin Spear, Orlando Sentinel
11:55 a.m. EDT, May 23, 2010

Oil company BP used a cheaper, quicker but potentially less dependable method to complete the drilling of the Deepwater Horizon well, according to several experts and documents obtained by the Orlando Sentinel.

“There are clear alternatives to the methods BP used that most engineers in the drilling business would consider much more reliable and safer,” said F.E. Beck, a petroleum-engineering professor at Texas A&M University who testified recently before a U.S. Senate committee investigating BP’s blown-out well in the Gulf of Mexico.

He and other petroleum and drilling engineers who reviewed a log of the Deepwater Horizon’s activities obtained by the Sentinel described BP’s choice of well design as one in which the final phase called for a 13,293-foot-long length of permanent pipe, called “casing,” to be locked in place with a single injection of cement that can often turn out to be problematic.

A different approach more commonly used in the hazardous geology of the Gulf involves installing a section of what the industry calls a “liner,” then locking both the liner and a length of casing in place with one or, often, two cement jobs that are less prone to failure.

The BP well “is not a design we would use,” said one veteran deep-water engineer, who would comment only if not identified because of his high-profile company’s prohibition on speaking publicly about the April 20 explosion aboard the Deepwater Horizon or the oil spill that started when the drilling rig sank two days later.
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This is just a rough overview of the current Deepwater Horizon blowout status. Don’t take any of these facts as quotable, though most are roughly correct, but if you need real sources, use real sources, don’t rely on a blog posting like this. I have made an effort to avoid the more common errors I’m seeing online currently, but some of these numbers are speculative at this point, nobody actually knows for a fact. But if you just want to get an idea of what’s going on now, today, this is basically the story. And you can also follow the ongoing TheOilDrum.com blowout thread.

Current Blowout Status

The 100k per day flow rates being tossed around on the internet are technically impossible, apparently the well, if totally open and free flowing, has something like a 60k per day maximum flow rate, but it’s not open, it’s partially restricted by the partially closed BOP valve, and then later on, by the crimps in the riser tube. From what I’m reading from oil engineers who have been posting on theoildrum.com, the most realistic flow rates of petroleum would be around 20k to 30k barrels per day, although it could be more in a worst case scenario. ROCKMAN and shelburn both seem comfortable with that range of estimate. A lot more than 5k reported, but it’s important to keep hyperbole on such events under control, especially when the numbers simply aren’t technically feasible. The stuff coming out is passing through what at least started out as a relatively small hole with something like 12k pounds per square inch pressure behind it, then that goes to the riser pipe,where it’s a bit more restricted by the bends. But the problem is that as the stuff comes out under that high pressure, it contains sand and grit, which expands the hole. That’s why the flow rates have increased consistently, and it’s what BP is actually worried about, the entire BOP / riser failing, and the unrestricted flow entering the gulf.

That’s why they are trying the top kill CNN, includes video animation of top kill method) stuff, but it’s also why it’s taking a long time, if it fails and ruptures the BOP unit, that would make the current spill look like child’s play, and there’d be no way to fix it until the relief wells hit. The mud will be pumped in at using 30k per square inch compressors, and since it’s denser than the oil, and because the BOP is partially closed (restricted flow, that is), the idea is the drilling mud will first rise to the BOP seal, fail to flow fast enough to pass it, being too thick, then go back down the well, since the compressors have greater force than the downhole pressure. If this works, whew. If not, worst case, the damaged bop unit blows out totally and we have unrestricted maximum flow rates for 2 months or more.

The top kill requires running pipes down to the ocean floor, hooking them up to massive compressors, capable of generating 30k pounds per square inch pumping pressures, then hooking those pipes up to 2 3″ inlets below the cutoff section of the BOP, then pumping in heavy drilling mud until it fills the down hole part of the well, thus blocking the upward flowing oil/gas mixture, after which the hole can be cemented shut. Difficult to do, and never done before at this depth.

New information (24 May 2010 18:39 GMT): top kill set for Wednesday BP says. This article has a lot of new information in it. Things are changing fast, hard to keep up.

If the top kill is not successful it could erode the riser and increase the flow from the well, Suttles said.

In case that happens, BP plans to immediately employ another cap on the well, a change from the plans Suttles announced Friday.

Friday Suttles said BP’s next option would be a junk shot, clogging the BOP with heavy fluids and debris like shredded tyres.

BP was attempting a top kill before a junk shot because a failed junk shot could cut off other well control options, Suttles said.

Now, the UK supermajor plans to cut off the riser from the lower marine riser package (LMRP) and attach another dome to collect the flow.

The “LMRP cap” would allow BP to capture as much of the flow from the well as possible while it works on other options to kill the well.

This is a fairly good summary of the sequence of events of the blowout, by shelburn.
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